Shanahan said Tuesday after the briefing on Iran that Pentagon has had deterred possible attacks by deploying forces to the region, Reuters reported.
"We have deterred attacks based on our reposturing of assets — deterred attacks against American forces. Our biggest focus at this point is to prevent Iranian miscalculation", Shanahan told reporters on Capitol Hill, quoted by Reuters. "This is about deterrence, not about war. We are not about going to war. This is about continuing to protect our interest in the Middle East", Shanahan told reporters on Tuesday.
Meanwhile, Republican US Senator Lindsey Graham said Tuesday that top administration officials told senators in a briefing the recent attacks on shipping and a pipeline in the Middle East was directed by Tehran.
"They explained to us how the Iranian threat streams were different than in the past, that the attack on the ships and the pipeline was coordinated and directed by the Iranian government, the Ayatollah", Graham told reporters, quoted by Reuters.
Earlier this month, two Saudi oil tankers and two other vessels were targeted in a mysterious attack in the United Arab Emirates' (UAE) exclusive economic zone. No casualties or environmental damage were reported after the incident. In addition, Yemeni Houthi rebels carried out drone attacks against a Saudi oil pipeline, causing fire and minor damage.
The Pentagon has stepped up its military forces in recent weeks in the Middle East in what US National Security Adviser John Bolton has called "a clear and unmistakable message" to Iran. The new US deployments in the region include a carrier strike group, Patriot missiles, B-52 bombers and F-15 fighters, according to the Pentagon.
US-Iranian tensions first flared up last year when the United States unilaterally withdrew from the 2015 nuclear agreement with Iran and started reinstating sanctions. On 8 May, Iran announced its decision to partially discontinue its obligations under the nuclear agreement.