Trade Tensions With China Heating Up Again HONG KONG - A month after Vice President Xi Jinping's visit to the United States and Europe, the brief trade policy détente between China and its two biggest export markets is about to end. Five separate issues - involving auto parts, cars, solar panels, anti-subsidy laws and rare earth metals - are all likely to see action by American officials, European officials or both, starting as soon as this week. On Tuesday, in fact, the United States and the European Union plan to file a formal "request for consultations" with China at the World Trade Organization about Chinese restrictions on exports of rare earth metals, according to people briefed on the issue. Such a request is the first step in a process that could lead to a full-fledged legal case at the W.T.O. by early summer, unless China unexpectedly agrees to the West's demands to ease the export of rare earths - materials vital to various sophisticated technologies. That move and the other trade issues are likely to meet Chinese resistance, particularly as senior officials in Beijing are jockeying for position ahead of a Communist Party conclave this autumn that is expected to choose a slate of leaders for the country for the next five years or more. Compounding the trade tensions is the prospect of revived frictions over China's currency policies. After rising fairly consistently against the dollar for nearly two years, helping quiet Western criticism that Beijing has kept the renminbi artificially low, the currency has begun to weaken again, making Chinese exports more competitive on the global market. On Monday, the Chinese currency fell further against the dollar, after China's central bank lowered its daily target for the currency. It has now fallen 0.5 percent against the dollar so far this year, after rising 4.7 percent last year. For the last month, American and European officials had mostly deferred action on trade tensions with China. The United States, seeking a good start with Mr. Xi, who is expected to become China's top leader next winter, postponed acting on the solar panel trade dispute until March to avoid colliding with the Chinese official's Valentine's Day visit to the White House. But China is seldom popular during election years in the United States, and this year is no exception. Mitt Romney and Congressional Democrats and labor unions have little in common politically - except that they have all called for tough trade policies toward China. It would be politically difficult for the White House to ignore the outcry. The European Union, for its part, has also been fairly quiet in the last month about Chinese trade policies, as it lobbied for a public commitment of Chinese money to ease the European debt crisis. But that sense of crisis has cooled somewhat, now that Greece has succeeded in reaching a debt reduction deal with its private creditors. And senior European Union officials have concluded that even if Beijing does decide to lend money toward a European bailout after two years of resistance, it would not be enough to make a significant difference, according to a person with a detailed knowledge of European deliberations on the issue who was not authorized to comment publicly. The Chinese commerce ministry had no comment Monday on the American and European trade tensions. Few if any trade issues between the West and China have been as acrimonious in the last several years as rare earth metals, which are crucial to a wide range of sophisticated technologies, from iPhones and energy-efficient lighting to electric cars and smart bombs. China has shown a willingness to use its near monopoly on rare earth production as a trade weapon, sharply reducing shipments to the West through export taxes and quotas that have forced many companies to move factories to China. The United States and European Union now plan to challenge those export taxes and quotas. Their legal filing at the W.T.O. in Geneva on Tuesday is also expected to include tungsten, a metal used to harden steel and other materials. China is the world's leading producer of tungsten and has restricted tungsten exports as well. Japan will join the United States and European request for W.T.O. consultations on rare earths, people involved in the discussions said. Japan has avoided W.T.O. cases against China until now, wary of antagonizing its much larger neighbor or of reawakening Chinese hostility over Japanese atrocities during World War II. But the rare earth embargo in 2010 was a deeply emotional issue in Japan, reminding many there of how dependent their island nation is on imported natural resources. A W.T.O. appeals panel ruled in late January that China must eliminate its export taxes on nine widely used industrial materials, not including rare earths or tungsten. The panel strongly criticized China's export quota system, saying the policies favored Chinese domestic manufacturers over their global competitors that also need the same raw supplies. The panel did leave open the possibility that the separate system of quotas could be reformed instead of being scrapped entirely. Chinese trade officials are to join the W.T.O."s monthly dispute-settlement meeting for all member nations in Geneva on March 23 to discuss the matter.