Is This an ERISA Welfare Plan?

[Scott]

Company A acquired a division of Company C, an unrelated entity. Some of the employees of the division who were eligible for retirement under Company C's plans retired from Company C prior to closing, so that they could begin receiving their pension benefits and begin coverage under Company C's retiree health plan. After the acquisition, some of those "retired" employees went to work for Company A. Company A reimburses those employees for a portion (but not all) of the premiums they must pay to Company C for their retiree health coverage.

Question: Has Company A established a "welfare benefit plan" under ERISA? In other words, is the mere reimbursement by an employer of a portion of the premiums paid by employees for health insurance which is not provided by the employer a welfare plan?

Any thoughts would be much appreciated.