Two top Yemeni security officers and four police escorts were killed when their car was ambushed on Tuesday by unidentified militants in the southeast of the country, where al- Qaida has been gaining strength. Ahmed Salim al-Ammary, director of the General Security Services (GSS) in Hadramout province, and Ahmed Ba-Wazir, head of the Political Security Organization (PSO) in Hadramout, were killed on board with their four security escorts in an ambush along the highway, said a senior security source who asked to remain anonymous. (Yemen-Ambush) WASHINGTON -- President Barack Obama said Tuesday that the United States and the European Union have agreed to redouble their efforts to ensure success of the climate change conference in Copenhagen this December. 'All of us agreed that it is imperative for us to redouble our efforts in the weeks between now and the Copenhagen meeting to assure that we create a framework for progress in dealing with (a) potential ecological disaster,' Obama told reporters after meeting with top EU officials in the White House. (US- Obama- Climate Change) UNITED NATIONS -- UN Secretary-General Ban Ki- moon on Tuesday said that he 'is dismayed at continued Israeli actions' on settlements in occupied Palestinian territory, and called on Israel to 'cease such provocative actions.' A statement, issued here by Ban's spokesperson, said, 'The secretary-general is dismayed at continued Israeli actions in occupied East Jerusalem, including the demolition of Palestinian homes, the eviction of Palestinian families and the insertion of settlers into Palestinian neighborhoods.' (UN-Israel) PRAGUE -- Czech President Vaclav Klaus on Tuesday signed the Lisbon Treaty shortly after the country's top court approved the pact, removing the last obstacle to full ratification of the treaty. 'I announce that I signed the Lisbon Treaty at 1500 (1400 GMT) today,' Klaus told reporters shortly after the Czech Constitutional Court ruled that the treaty did not contradict the country's constitution. (Czech Republic-Lisbon Treaty) 