COMMITMENTS AND CONTINGENCIES Operating Leases We have non-cancelable operating lease agreements for office, research and development and manufacturing space in the United States and foreign locations. We also have operating leases for certain equipment and services in the United States and foreign jurisdictions. These lease agreements expire at various dates through 2029 , and certain agreements contain provisions for extension at substantially the same terms as currently in effect. Lease escalation clauses, rent abatements and/or concessions, such as rent holidays and landlord or tenant incentives or allowances, are typically included in the determination of straight-line rent expense over the lease term. Future minimum lease payments for the next five fiscal years as of September 27, 2019 , are as follows (in thousands): Fiscal year ending: Amount 2020 $ 9,987 2021 9,233 2022 7,447 2023 6,061 2024 5,564 Thereafter 16,437 Total minimum lease payments $ 54,729 Rent expense incurred under non-cancelable operating leases was $9.7 million , $9.5 million and $10.9 million in fiscal years 2019 , 2018 and 2017 , respectively. Asset Retirement Obligations We are obligated under certain facility leases to restore those facilities to the condition in which we or our predecessors first occupied the facilities. We are required to remove leasehold improvements and equipment installed in these facilities prior to termination of the leases. As of the end of fiscal years 2019 and 2018 , the estimated costs for the removal of these assets are recorded as asset retirement obligations in other long-term liabilities were $1.8 million and $1.8 million , respectively. Purchase Commitments As of September 27, 2019 , we had outstanding non-cancelable purchase commitments aggregating to $40.6 million primarily for purchases of capital equipment, services and inventory supply arrangements. Litigation From time to time we may be subject to commercial disputes, employment issues, claims by other companies in the industry that we have infringed their intellectual property rights and other similar claims and litigations. Any such claims may lead to future litigation and material damages and defense costs. We were not involved in any material pending legal proceedings during the year ended September 27, 2019 .