WASHINGTON: U.S. Defense Secretary nominee Chuck Hagel said the "window is closing" on Iran and the possibility of diplomacy if it continues to ignore international demands to end pursuit of a nuclear weapon.

In his first opportunity to express his opinions since President Barack Obama nominated him Jan. 7, Hagel addressed a range of issues, from Iraq and Afghanistan to women in combat, in a 112-page questionnaire for the Senate Armed Services Committee. The panel submitted the questions to Hagel in advance of his confirmation hearing Thursday.

The former two-term Republican senator has faced a barrage of criticism that he is not sufficiently pro-Israel and tough on Iran. In his responses, Hagel adopted a hard line on Iran, echoing Obama's contention that the United States would consider all options, including military action, to keep Iran from acquiring a nuclear weapon.

"If confirmed, I will focus intently on ensuring that U.S. military is in fact prepared for any contingency," Hagel said in response to committee questions.

The United States and other Western nations have demanded that Iran stop its uranium enrichment program, which they perceive as a precursor to production of nuclear warhead-grade material. Iran insists that its program is for peaceful purposes.

The most recent round of negotiations ended in a stalemate last June.

"If Iran continues to flout its international obligations, it should continue to face severe and growing consequences," Hagel said. "While there is time and space for diplomacy, backed by pressure, the window is closing. Iran needs to demonstrate it is prepared to negotiate seriously."

In the past, Hagel has questioned the efficacy of unilateral sanctions on Iran, arguing that penalties in conjunction with international partners made more sense.

He said in his response to the committee that he would continue to implement the "smart, unprecedented and effective sanctions against the Iranian regime" that Congress and the Obama administration have adopted in recent years.