NEW YORK (Reuters) - France on Monday gave a staunch defense of the Iran nuclear deal, suggesting there could be talks to strengthen the pact for the post-2025 period but that allowing it to collapse could lead Iran s neighbors to seek atomic weapons.  It is essential to maintain it to avoid proliferation. In this period when we see the risks with North Korea, we must maintain this line,  French Foreign Minister Jean-Yves Le Drian told reporters.  France will try to convince (U.S.) President (Donald) Trump of the pertinence of this choice (keeping the accord) even if work can be done to complement the accord (after 2025),  he said.  Speaking on the sidelines of the U.N. General Assembly annual gathering of world leaders in New York, Le Drian said a collapse of the deal could lead to a regional arms race. Key U.S. allies are worried by the possibility of Trump effectively pulling out of the landmark 2015 nuclear deal under which Iran agreed to curb its nuclear program in exchange for relief from economic sanctions. Le Drian also made clear France s opposition to an Iraqi Kurdish independence referendum, saying Iraq s constitution had important provisions on the autonomy of the Kurdistan region of northern Iraq and  all other initiatives are inappropriate.  He also said the five permanent members of the U.N. Security Council   Britain, China, France, Russia and the United States   on Thursday would discuss the possibility of a contact group on Syria, now in its seventh year of civil war. 