The phrase "an assertive role" is correct and usable in written English.
It can be used when describing a position or function that involves confidence and decisiveness in actions or decisions.
Example: "In her new position, she took on an assertive role in leading the team towards achieving their goals."
Alternatives: "a proactive role" or "a confident role".
The infiltration suggests that Iran may be trying to take an assertive role in shaping developments.
That assumes Washington will take an assertive role in reshaping regulations.
International relations highlighted Angola's desire for an assertive role in continental affairs.
He wants to be more aggressive, take an assertive role as far as being one of our leaders.
Relatively poor, with a population that pales before countries like Egypt, Syria has long played an assertive role in the region by making itself a linchpin.
Brazilian diplomats have staked out an assertive role in preliminary talks, resisting proposals from rich industrialized countries that developing nations should be required to pay more to reduce environmental degradation.
Abbott, who has been playing an increasingly assertive role in security debates, used a speech in Singapore on Wednesday evening to call for increased military action in Iraq and Syria to prevent "the persistence of a blood-soaked caliphate killing in the name of God".
Indonesia joined the G20, took an increasingly assertive role in climate-change talks and encouraged pluralism among developing countries at the Bali Democracy Forum.
Japanese Prime Minister Junichiro Koizumi is one of President Bush's closest allies, and Rice's speech comes as Japan has claimed an increasingly assertive role on the world stage.
As American envoys today completed a first day of talks to persuade North Korea to abandon its nuclear weapons program, China appeared to be playing an unusually assertive role in pressing both sides to keep open lines of communication even if an initial round of discussion produces no breakthrough.
"We need to be honest about the level of failure for the past eight years and why Republican government didn't succeed," said Newt Gingrich, the former House speaker, who has played an increasingly assertive role in the debate over the party's future.
