Secretary of State Hillary Rodham Clinton on Monday offered a vigorous defense of the new U.S. plans for missile defense.

In an op-ed in the London-based Financial Times, Clinton also sought to assure allies in NATO that the decision by President Barack Obama to pull back plans for a long-range missile defense system did not mean the U.S. was moving away from protecting Eastern Europe.

"We are not walking away from our allies but are deploying a system that enhances allied security, advances our cooperation with NATO and actually places ore resources with more countries," Clinton wrote.

The decision, a sharp turn from Bush administration policy, has sparked criticism from Republicans. Poland and the Czech Republic, which were to house the missile defense system, also were unnerved by Obama's decision to shelve plans for the long-range system, and Clinton sought to provide assurances to those two countries.

She said the U.S. "deeply appreciated" their willingness to house parts of the previously planned system. "We will continue to cooperate closely with both nations and both will have the opportunity to be closely involved with missile defense," she wrote.

To read Clinton's op-ed, click here.